A woman leaped from the third deck of the O.co Coliseum after the Oakland Raiders lost Sunday, injuring herself and a man who heroically tried to catch her and save her life, the Alameda County Sheriff's Office said.

The woman was knocked unconscious in the fall and her identity was not immediately known, said sheriff's Sgt. J.D. Nelson. The woman was in critical condition at a local hospital, Nelson said.

The Good Samaritan who tried to break her fall was also being treated for serious injuries, he said.

"Raiders fans sometimes get a bad rap, but here was this guy who did an amazing, heroic thing to try to save this woman's life," Nelson said. "He did everything he could, including putting himself at great risk. There's not a lot of people who would do that, and he did it."

About 15 minutes after the Raiders lost a heartbreaker to the Tennessee Titans, the woman climbed to the top of section 301, an upper deck area above the south end zone that is covered by tarp and closed to the public, he said.

There she stood for a couple of minutes facing the parking lot, looking over the second-deck concourse about 50 feet below, Nelson said.

Two men on the concourse unsuccessfully tried to persuade her not to jump, but when she did, one man attempted what would have been the best catch of the day.

"We don't believe that he knew her from anybody else going into today, but just out of the goodwill of his heart, he tried to save her life," Nelson said. "No doubt he saved her life, at least for right now."

Officials don't know why the woman jumped. In a statement, the Raiders said that no other information was available "for reasons of privacy and the ongoing investigation."

Last week, two men attending a Buffalo Bills-New York Jets game at Ralph Wilson Stadium in Orchard Park, N.Y., were injured when one man sliding down a railing in the 300 level slipped and fell to a lower deck, landing on the other man.